Presentation Transcript

Cellular Division :

1 Cellular Division

Cell Division :

2 Cell Division All cells are derived from pre-existing cells
New cells are produced for growth and to replace damaged or old cells
Differs in prokaryotes (bacteria) and eukaryotes (protists, fungi, plants, & animals)

Keeping Cells Identical :

3 Keeping Cells Identical The instructions for making cell parts are encoded in the DNA, so each new cell must get a complete set of the DNA molecules

DNA Replication :

4 DNA Replication DNA must be copied or replicated before cell division
Each new cell will then have an identical copy of the DNA Original DNA strand Two new, identical DNA strands

Identical Daughter Cells :

5 Identical Daughter Cells Parent Cell Two identical daughter cells

Chromosomes :

6 Chromosomes

Prokaryotic Chromosome :

7 Prokaryotic Chromosome The DNA of prokaryotes (bacteria) is one, circular chromosome attached to the inside of the cell membrane

Eukaryotic Chromosomes :

8 Eukaryotic Chromosomes All eukaryotic cells store genetic information in chromosomes
Most eukaryotes have between 10 and 50 chromosomes in their body cells
Human body cells have 46 chromosomes or 23 identical pairs

Eukaryotic Chromosomes :

9 Eukaryotic Chromosomes Each chromosome is composed of a single, tightly coiled DNA molecule
Chromosomes can’t be seen when cells aren’t dividing and are called chromatin

Compacting DNA into Chromosomes :

10 Compacting DNA into Chromosomes DNA is tightly coiled around proteins called histones

Chromosomes in Dividing Cells :

11 Chromosomes in Dividing Cells Duplicated chromosomes are called chromatids & are held together by the centromere Called Sister Chromatids

Karyotype :

12 Karyotype A picture of the chromosomes from a human cell arranged in pairs by size
First 22 pairs are called autosomes
Last pair are the sex chromosomes
XX female or XY male

Boy or Girl? :

Cell Reproduction :

14 Cell Reproduction

Types of Cell Reproduction :

15 Types of Cell Reproduction Asexual reproduction involves a single cell dividing to make 2 new, identical daughter cells
Mitosis & binary fission are examples of asexual reproduction
Sexual reproduction involves two cells (egg & sperm) joining to make a new cell (zygote) that is NOT identical to the original cells
Meiosis is an example

Early Prophase :

Late Prophase :

32 Late Prophase Nuclear membrane & nucleolus are broken down
Chromosomes continue condensing & are clearly visible
Spindle fibers called kinetochores attach to the centromere of each chromosome
Spindle finishes forming between the poles of the cell

Late Prophase :

33 Late Prophase Nucleus & Nucleolus have disintegrated Chromosomes

Spindle Fiber attached to Chromosome :

34 Spindle Fiber attached to Chromosome Kinetochore Fiber Chromosome

Review of Prophase :

35 Review of Prophase What the cell looks like What’s happening

Spindle Fibers :

36 Spindle Fibers The mitotic spindle form from the microtubules in plants and centrioles in animal cells
Polar fibers extend from one pole of the cell to the opposite pole
Kinetochore fibers extend from the pole to the centromere of the chromosome to which they attach
Asters are short fibers radiating from centrioles

Sketch The Spindle :

37 Sketch The Spindle

Metaphase :

38 Metaphase Chromosomes, attached to the kinetochore fibers, move to the center of the cell
Chromosomes are now lined up at the equator Pole of the Cell Equator of Cell

Metaphase :

39 Metaphase Chromosomes lined at the Equator Asters at the poles Spindle Fibers

Cytokinesis :

Mitotic Stages :

49 Mitotic Stages

Daughter Cells of Mitosis :

50 Daughter Cells of Mitosis Have the same number of chromosomes as each other and as the parent cell from which they were formed
Identical to each other, but smaller than parent cell
Must grow in size to become mature cells (G1 of Interphase)

Identical Daughter Cells :

51 Identical Daughter Cells Chromosome number the same, but cells smaller than parent cell What is the 2n or diploid number? 2

Review of Mitosis :

52 Review of Mitosis

Name the Mitotic Stages: :

Eukaryotic Cell Division :

54 Eukaryotic Cell Division Used for growth and repair
Produce two new cells identical to the original cell
Cells are diploid (2n) Chromosomes during Metaphase of mitosis Prophase Metaphase Anaphase Telophase Cytokinesis

Mitosis Animation :

55 Mitosis Animation Name each stage as you see it occur?

Mitosis in Onion Root Tips :

56 Mitosis in Onion Root Tips Do you see any stages of mitosis?

Draw & Learn these Stages :

57 Draw & Learn these Stages

Draw & Learn these Stages :

58 Draw & Learn these Stages

Test Yourself over Mitosis :

59 Test Yourself over Mitosis

Mitosis Quiz :

60 Mitosis Quiz

Mitosis Quiz :

61 Mitosis Quiz

Name the Stages of Mitosis: :

62 Name the Stages of Mitosis: Interphase Early prophase Mid-Prophase Late Prophase Metaphase Late Anaphase Early Anaphase Early Telophase,
Begin cytokinesis Late telophase,
Advanced cytokinesis

Locate the Four Mitotic Stages in Plants :

Uncontrolled Mitosis :

65 Uncontrolled Mitosis If mitosis is not controlled, unlimited cell division occurs causing cancerous tumors
Oncogenes are special proteins that increase the chance that a normal cell develops into a tumor cell Cancer cells

MeiosisFormation of Gametes (Eggs & Sperm) :

66 MeiosisFormation of Gametes (Eggs & Sperm)

Facts About Meiosis :

67 Facts About Meiosis Preceded by interphase which includes chromosome replication
Two meiotic divisions --- Meiosis I and Meiosis II
Called Reduction- division
Original cell is diploid (2n)
Four daughter cells produced that are monoploid (1n)

Facts About Meiosis :

68 Facts About Meiosis Daughter cells contain half the number of chromosomes as the original cell
Produces gametes (eggs & sperm)
Occurs in the testes in males (Spermatogenesis)
Occurs in the ovaries in females (Oogenesis)

Why Do we Need Meiosis? :

70 Why Do we Need Meiosis? It is the fundamental basis of sexual reproduction
Two haploid (1n) gametes are brought together through fertilization to form a diploid (2n) zygote

Fertilization – “Putting it all together” :

71 Fertilization – “Putting it all together” 1n =3 2n = 6

Replication of Chromosomes :

72 Replication of Chromosomes Replication is the process of duplicating a chromosome
Occurs prior to division
Replicated copies are called sister chromatids
Held together at centromere Occurs in Interphase

A Replicated Chromosome :

73 A Replicated Chromosome Gene X Homologs separate in meiosis I and therefore different alleles separate.

Meiosis Forms Haploid Gametes :

74 Meiosis Forms Haploid Gametes Meiosis must reduce the chromosome number by half
Fertilization then restores the 2n number The right number!

Telophase II :

Results of Meiosis :

91 Results of Meiosis Gametes (egg & sperm) form
Four haploid cells with one copy of each chromosome
One allele of each gene
Different combinations of alleles for different genes along the chromosome

Gametogenesis :

92 Gametogenesis Oogenesis or Spermatogenesis

Spermatogenesis :

93 Spermatogenesis Occurs in the testes
Two divisions produce 4 spermatids
Spermatids mature into sperm
Men produce about 250,000,000 sperm per day

Spermatogenesis in the Testes :

94 Spermatogenesis in the Testes Spermatid

Spermatogenesis :

95 Spermatogenesis

Oogenesis :

96 Oogenesis Occurs in the ovaries
Two divisions produce 3 polar bodies that die and 1 egg
Polar bodies die because of unequal division of cytoplasm
Immature egg called oocyte
Starting at puberty, one oocyte matures into an ovum (egg) every 28 days